I would like to make a note here that, as I read this list, all of these come down to cost. As constraints, I think it is important to recognize you are optimizing for cost. Which is wise.
And here is where I think you might want to start reexamining your observed constraints.
Like, what if you can build a bigger boat, for the price of a smaller boat? What if you could have the much more pleasant ride, safety, and payload of bigger boat, with the costs and weight of a smaller?
Your assessment that many of my choices are cost based. I'm a poor man by the standards of yachties. I expect to be living on a very limited retirement income once I "cut loose". The plan is NOT to have a home base at all, and spend the rest of my life until I am unable, as a wanderer of the world's oceans. My many years of fixing machinery and almost anything else, as well as designing and building machinery, etc, should serve me well, making maintaining my boat and it's systems easy for me, and likely supplementing my income a bit as well. Engines and drive systems are a large part of what work with, as well as hydraulic systems, electrical & control systems, pumps, structural design, welding, etc. Some of these things are in demand in the yachting community.
These are the questions I started asking myself.
These kind of questions also lead me to the junk rig. (Aside; have you joined the junk rig association?). Because it allowed me to have the skills to actually make my own sails! Out of inexpensive materials. ( I have a life habit of doing my own maintenance too!). But I thought it smart to be able to fix all the crap on the contraption I depend on.
Another aside; I found Mr. Woods not very supportive of junk rigs. Or strange masts I could build myself.
I'm not actually a member of the JRA, but I know many of the members, and visit the site regularly. Arne is a valuable asset, and his articles are well worth reading. He drew up a junk rig for Sagitta based on the original mast location, and assuming that I could work out the structural issues of the mast partner (where it goes through the coach roof).
The rig that interests me most is Paul McKay's Aerojunk, which is the rig that Pete Hill ultimately ended up with on his biplane 10M stretched KD 860, Oryx. The Aerojunk uses batten cages, rather than battens, and a flat sail flying inside this "cage" that takes it's camber by laying against the battens. These battens are actually quite light, as their dimensions allow them to be strong without being heavy.
The split rig offers a bit more drive efficiency, and it takes the mast out of the equation, so it does not lay in the sail on one tack, and in the case of Paul's Aerojunk, the entire batten cage & sail shifts considerably, eliminating the turbulence of the air across the mast. I have an idea to take this a step further so that the mast can be used to actually contribute lift, not just produce drag and turbulence....... I won't try to describe it here, though it's fairly simple.
I look at my 30' parameter, and the most I can get from it in a multihull. The cat has narrower hulls, but two of them, a far larger cockpit, and the bridge deck cabin on a level with the cockpit... . I look at payload, not just displacement. Dead weight / excess boat weight is a liability. It means more drag, slower sailing, and a bigger rig, larger motor(s), etc.
How do you compare a cat and a tri? Per foot? Or displacement? Or cost? Or accommodations?
I think, as a single hander, I would just reef, and goto sleep. Wake up, set sail, and put coffee on.
Although I recently had a new sleeping concern.
https://m.youtube.com/watch?v=hHjbdOh8qDg
Realistically, there are times when one will want to do this, and others when one will want to keep sailing. Sleeping under sail is always a gamble, but the odds are stacked heavily in our favor with the technology we have today such as AIS. Radar is pretty useless IMHO except for weather. AIS will pick up all commercial shipping, and nearly all yachts while on a passage. Close to land is where the problems are. Hopefully in coastal sailing, one will be able to make anchorages often enough not to have to sleep between. I tend to sleep in short spells anyway, waking up every hour or two. Only time will tell what patterns will develop. I'm not one to be in a hurry, I got over that many years ago. Another few days on a long passage won't bother me I'm sure. I'm well adapted to solitude, for me, sailing is about sailing, not rushing from one crowded anchorage to the next. When I do anchor at one of those places, it will be for supplies and mail. My natural inclination is to seek out the quiet places with a few fishing boats, or nobody at all.
Putting the masts in the hulls simplify the structure. I had thought about one mast in one hull. I still don't know why that wouldn't work.
Asymmetry doesn't bother me, in fact I'm attracted to it. However it really doesn't work to put the mast in one hull of a cat. The natural progression of thought here is that since the mast is in one hull, the accommodations should be in the other for counter weight, which leads into having two dissimilar hulls, all of which is OK. The desire to always have the sail over the boat, and not reaching far outboard to catch waves, leads into shunting, which is OK also. Rob's variant of having the accommodation hull without the mast, and the mast hull is a good one IMHO. Proas are in fact just asymmetric cats........... or vice versa.
The complexity of the balance of the thrust and control vectors bothered me.. It seemed a design was a better fit if it started from the ground up with the intention of the stated goals.
Climbing the wrong side of the design spiral is costly.
I have reluctantly come to the realization as you state that it is desirable to start from the ground up to achieve my goals, and actually have begun a scale model, as well as some full size mockups to examine internal dimensions in terms of how much space is needed and how best to utilize it. I'm shopping for some used cheap trailerhouse type paneling with the idea of building a full scale mockup of one hull. Starting from the ground up is not completely accurate, as I intend to borrow ideas (structural and layout) wherever I can find them. I've put together a pretty complete "structural picture" of what it will take. There is more than enough data, and photos, etc to do that, not to mention study plans that allow one to get an idea how the designers have solved the various problems that are not unique to this project.
As I mentioned before the KD 860's trapezoidal hulls appeal to me. Pete Hill's Oryx improved on these by incorporating a ridge / wing, or whatever you want to call it, at countertop level, greatly improving the utility of the main hull areas by providing two flat surfaces instead of one, and did it elegantly. Note the photos below for comparison. The two center ones are Oryx, and note that it is 10 M, not 8.6, so the galley counter is much longer. While my boat will be 1M shorter, I plan to borrow some of Pete's ideas, including this step. The portlights will be higher to allow good side visibility from the bridge deck cabin. It appears that Pete also lifted the cabin sole a few inches making it wider, note the two lift out panels in the photo. The photo of Oryx is looking aft, and note that the head is where it should be, not in the bow. The engine is right behind the composting toilet. The photo on the right is a "stock" KD 860 looking forward. Behind the doorway is the master berth. My inclination is to widen the two hulls a slightly to increase displacement per inch of draft, as speed is NOT one of my priorities. The boat will be 30 feet instead of 28, and the added length will show up in the galley & saloon, and the aft hulls, allowing an aft berth in the port hull. On the KD 860, the forward bulkhead in the saloon is a main structural bulkhead, and the bulkhead forward of that is also a structural bulkhead, and serves as the mast beam. This forward space is two double berths, and takes up about 4 1/2 feet of length. The curved leading edge of the bridge deck joins the mast beam with some longitudinal bulkheads, adding to it's stiffness and strength, and a longitudinal divider bulkhead between the two forward berths joins it all to the forward bulkhead of the saloon. The saloon seating is a structural part of this bulkhead, the whole making for a very strong and stiff structure. I would move the saloon bulkhead forward about a foot, and step the mast on the forward face of it, allowing it to carry the lateral loads on the mast, and of course "enhancing" it a bit. The longitudinal bulkhead would be doubled to become two bulkheads, one either side of the mast, and carry much of the fore and aft mast loads forward to the original mast bulkhead, which would then deliver these loads as vertical loads to the hulls.... as it is designed to do originally. The saloon is now 7' fore and aft, as is the galley, and structure built into the galley and chart room counters and stowage will function as additional hull support bulkheads, the sole being lifted a few inches to allow tie across beneath it in the bilge. This will also create some bilge stowage, which is where heavy stuff should be. The aft bulkhead of the bridge deck cabin is cut away with 3 companionways with sliders in the original drawings, making it non structural. I intend to make it an additional structural bulkhead. At the aft end of the cockpit is a major beam for the traveler. No traveler is needed for a junk rig, but the beam is necessary and useful anyway, and will mount the dinghy lift.
This is all preliminary ideas........... In designing and building things, I've always worked most of the details out in my head in advance, and mentally run the machine / sailed the boat, many times before I ever even put anything on paper. One project about 14 years ago involved 6 months build time and 5 people, $36K in materials. Much detail was not resolved in advance, though there was enough to get started. I lived, breathed, and slept that project for 6 months, staying far enough ahead that every day we could work with confidence that we would not have to redo anything. It was a complex project involving putting together a diesel power train, hydraulics, electric and air control systems, limits and safety interlocks, and in the end I put together a complete book of over 200 pages of details and drawings, as well as the rationale for doing things the way I did them, to make it possible for others to understand and maintain it. 14 years later, it is still in daily use. I would be a liar if I claimed it was without initial glitches, but those were quickly resolved. A few minor control systems were redesigned for operator convenience. It's on it's third owner, as the business has changed hands.
The challenge here is locating the mast. Ideally the mast would go forward of it's original location for several reasons. I may be forced to step it in the original location, and use struts in lieu of bury. That's doable, but not pretty.
I don't know this is true. I assert that it is cheaper to build in foam and glass, assuming Intelligent Infusion. One still has to glass both sides of the plywood or the foam. Infused glass and foam takes much less epoxy, and that is the most expensive item. No throw away frames or jig to build or align, just a flat table and sawhorses. Certainly work saved counts for something.
I don't see how one can build half a hull in one shot on a flat table. Looking at the drawing and photo above, there are 3 or 4 intersecting plains involved. You have half the bottom, the lower side, and the upper side, and in the case of a hull like Oryx, a shelf. The whole idea as I understand it is to to the hulls in halves and join them. I'm seeing a complex box mold, not a simple flat table. What am I missing? The idea is NOT to have to make a bunch of joints to fair.
I also have a limited objection to the assertion of ongoing higher costs of a bigger boat. While generally true, there are some exceptions, which Rob has optimized. Assuming a typical Denny design, what costs are increased for a bigger boat?
The hull is lighter, so more easily driven. The durability and wear should favour the lighter boat. The only real direct cost I can think of is the marina fees, to which Rob has an integrated generous tender to mitigate. I can think of no other costs.
Finally, I assert a bigger boat can be cheaper than a smaller boat. I dare you to compare BOM's, for just the hull costs and sails, for the most similar accommodations to the designs you stated.
Then look at the one with the most similar payload.
Larger rigs mean heavier everything from cordage to blocks, to larger sails, etc....... All of these things must be replaced / maintained. Likewise there is more bottom to paint and maintain, and more top and interior. Heavier ground tackle, which costs more to buy and maintain, even more fenders, etc. Bigger engines, more fuel to buy and store, etc. Then there is a greater likelihood that some lady will be attracted to a guy with a bigger boat, and all the attendant expenses that go with that ;-) No, you will never sell me on the idea that a larger boat may not cost more on an ongoing basis.
H.W.
Posted by: StoneTool <owly@ttc-cmc.net>
| Reply via web post | • | Reply to sender | • | Reply to group | • | Start a new topic | • | Messages in this topic (88) |